Tubiflorce. 161 
What vve must regard as a further and important primitive 
feature in Verbenaceae is the relatively low degree which the schizo- 
carpic tendency has attained in this family. The ovary is usually 
almost entire in external form, although its internal chambering 
into uniovulate compartments is active and unmistakeable. The 
result in the fruit is a chambered drupe; and this condition may 
be regarded as a primitive step towards the true schizocarpy 
characteristic of Labiatae. Each seed is protected independently, 
but cannot be dispersed independently from the outset. The same 
transition is observable in Boraginaceae, as witness the distinction 
between the drupaceous fruits of Cordioideae, Ehretioideae and 
Heliotropioideae, and the schizocarps of Boraginoideae. 
In view of the foregoing, we are led to place Verbenaceae 
relatively low in the evolutionary tree (see diagram, p. 152), in a 
position corresponding with that assigned to Bignoniaceae in the 
case of Multiovulatae. 
In regard to the special lines of evolutionary advance within 
the family, these are the reverse of distinct. In habit the Verbe¬ 
naceae display considerable diversity, as is to be expected in view of 
their relative primitiveness. They may be trees, shrubs, or herbs; 
lianes occur fairly commonly; but no general distinctive facies is 
peculiar to the family as a whole. Perhaps the most definite 
tendency is towards the close aggregation of florets, resulting in 
the common occurrence of spikes and heads, often associated with 
involucres of coloured bracts. The flowers are sometimes very 
large, in some cases with very long corolla-tubes ( Clerodendron ). 
The aggregation-tendency is particularly noticeable in the 
herbaceous forms, and we shall find it reflected as a common 
character in Labiatae. Before we deal with this family, we must 
refer briefly to the other two families which appear in Engler’s 
group B of Tubiflorae. 
Phrymaceae, containing a single species only, Phryma lepto- 
stachya, is included in Verbenaceae by Bentham and Hooker, but 
separated as a distinct family by Engler on the ground that the 
erect ovule is orthotropous, there being no transitional stages to 
this condition in Verbenaceae. The ovary is unilocular and uni¬ 
ovulate. The plant in question is herbaceous, with the habit and 
facies of Priva, a truly verbenaceous genus. It would be out of 
place to discuss in detail here the systematic position of Plirynia , 
but it may be suggested that the ovary may represent the remnant 
of an ancestral group of nucules, the rest having aborted—a process 
